力学学报

DEVOTION TO CHINESE SCIENCE-IN MEMORY OFPROFESSOR LIN TONGJI

As a famous scientist specialized in fluid mechanics, Professor Lin Tonggji had madeoutstanding contributions to rarefied gas dynamics, hypersonic and transonic aerodynamics, incom-pressible fluid dynamics, ablative thermal protection for re-entry flight vehicles and incompressibleoscillatory now which have found important applications in aeronautical and astronautical engi-neering and offshore engineering.Professor Lin was the vice-editor-in-chief and editor-in-chief of Acta Mechanica Sinica from1979 to 19...

1999, 31(6): 641-644. doi: 10.6052/0459-1879-1999-6-1995-076

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NOVEL COOLING MEANS FOR A CRYOGENICWIND TUNNEL

Existing cryogenic wind tunnels with cooling accomplished by spraying liquid nitrogendirectly into the tunnel circuit must equally discharge cryogenic gaseous nitrogen for keeping thesteadiness of the test flow. The tremendous "cool energy" carried away not only leads to heavydemands on liquid nitrogen and hence refrigerating power but also causes pollution of the localatmosphere.An alternative means of cooling air to cryogenic temperature by relying alone on the compres-sion energy of the air is presented....

1999, 31(6): 645-651. doi: 10.6052/0459-1879-1999-6-1995-077

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THREE-DIMENSIONAL STABILITY ANALYSIS OF THEPERIODIC WAKE BEHIND A CIRCULAR CYLINDERBY LOW-DIMENSIONAL GALERKIN METHOD

Three-dimensional linear instability of flow past a circular cylinder is analyzed bymeans of a low-dimensional Galerkin method and Floquet instability theory. Some improvementson the construction of the azimuthal modes and calculation algorithm in the present analysisare made. The present results show that the ideal two-dimensional periodic flow around thecylinder is unstable with respect to a small spanwise disturbance. It has long-wavelength instabilityand the critical Reynolds number predicted is Re_c =1...

1999, 31(6): 652-660. doi: 10.6052/0459-1879-1999-6-1995-078

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DISCUSSION ON PARTICLE SUSPENSION MECHANISM ANDSUSPENSION WORK

Any kinds of random motion of particulates (gas molecules, Brownian particles, etc.)can make them suspended in gravity field in spite of there are external forces or not. Suspension ofthe solid particles in rivers and in pipes of pneumatic (or hydraulic) transport is also supported bythe random motion of themselves. The lift and other forces acting on particles can really changethe vertical distribution of the particles, but they can not make the particles dispersedly suspendedif there are no random motion....

1999, 31(6): 661-670. doi: 10.6052/0459-1879-1999-6-1995-079

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PROGRAM MARKING OF SURFACE ELEMENTS ANDTHE DETERMINATION OF MOLECULAR SURFACEREFLECTION IN POSITION ELEMENTALGORITHM OF DSMC METHOD~1)'2)

In the position element algorithm of DSMC, the crucial questions to be solved arethe exact description of body surface configuration and precise determination whether a moleculecomes into collision with a certain surface element. Those issues are directly related to the accuracyin calculation of aerodynamic force and heating. In order to solve these questions, two innovationsconcerning the improvement of our position element version in the calculation of three-dimensiontransitional flow by the DSMC method a...

1999, 31(6): 671-676. doi: 10.6052/0459-1879-1999-6-1995-080

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SCOUR OF THE SAND BED BELOW THE PIPELINE INOSCILLATING FLOW

The Scour of the bed below a pipeline in oscillating flow is studied experimentally ina U-Shaped water tunnel with a sand box at the bottom of the test section. The artificial plasticsand is used as bed material. The relationship between the maximum equilibrium scour depth andKc number, and the relationship between the critical gap above which no scour occurs and Kcnumber are obtained. It is shown in this test that the critical amplitude in the presence of thepipeline at which the sand wave is formed is sma...

1999, 31(6): 677-681. doi: 10.6052/0459-1879-1999-6-1995-081

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EXPERIMENTAL INVESTIGATION OF THE WXKE OFAXISYMMETRIC BLUFF BODY AND ITS CONTROLBY MEANS OF ACOUSTIC FORCING~1)

Behaviors of the wake of an axisymmetric bluff body and its control by means ofacoustic forcing have been experimentally investigated for Reynolds numbers ranging from 3.0 χ10~3to 1.0 χ10~5.According to flow visualization, the flow separates at the rear of model, and the evolution ofseparated shear layer finally results in the belieal vortices shedding and forming the reverse flow.The length of recirculation region increases from Re = 3.0 χ 10~3 to Re = 2.0χ10~4, and remains aconstant of X_r/D = 0.975 in Re...

1999, 31(6): 682-693. doi: 10.6052/0459-1879-1999-6-1995-082

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STABILITY ANALYSIS ON SUPERSONICTRAILING-LINE VORTEX

In recent years there has been a great deal of interests in the stability of swirlingflows. It is because of not only the significance to the enhancement of supersonic mixing butalso the important applications to many practical flows such as the trailing-line vortices behindan aircraft. The absolute/convective instability of incompressible swirling flows and the temporalinstability of compressible swirling flows have been fully explored, whereas the absolute/convectiveinstability of compressible swirling fl...

1999, 31(6): 694-699. doi: 10.6052/0459-1879-1999-6-1995-083

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THE APPLICATION OF NUMERICAL SIMULATION INANALYSIS OF QIANTANGJIANG TIDEPart II: Result and Discussion

This paper is the second part of the present paper. For 1D situation, three numericalexamples, i.e. the computation of a problem with exact solution, numerical simulation of waterjump and collapsed-dam, are computed. The computation of problem with exact solution is usedto check the accuracy of the numerical method. The result of numerical simulation of water jumpindicates its applicability to describe the movement of nonlinear water wave by comparing withthe theoretical result. The result of break-dam comp...

1999, 31(6): 700-716. doi: 10.6052/0459-1879-1999-6-1995-084

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MULTI-VARIABLE VARIATIONAL PRINCIPLES FORPLATE BENDING AND PLANE ELASTICITY

In this paper, the multi-variable variational principles for plate bending and plane elas-ticity are presented, which included all the boundary integral formulas. The variational principlefor plate bending covers five classes of equations of equilibrium, bending moment function-bendingmoment, curvature-deflection, compatibility, bending moment-curvature and all boundary condi-tions, in which independent variables are deflection, curvature, non-homogeneous bending moment,bending moment functions and bending ...

1999, 31(6): 717-723. doi: 10.6052/0459-1879-1999-6-1995-085

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GENERALIZED CELL MAPPING DIGRAPH METHOD FORGLOBAL ANALYSIS

In this paper, according to Hsu's idea that posets and digraphs are introduced intogeneralized cell mapping, a generalized cell mapping digraph method is presented by using thetheory of generalized cell mapping discretizing the continuous state space into the cell state spaceand the theories of set and digraph to achieve the task of global analysis of nonlinear dynamicalsystems. In the cell state space, we make the correspondence between generalized cell mappingdynamical systems and digraphs. The demonstrat...

1999, 31(6): 724-730. doi: 10.6052/0459-1879-1999-6-1995-086

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A COMPREHENSIVE ALGORITHM FOR SHAPE OPTIMIZATIONOF STRUCTURE WITH DISCRETE VARIABLES

In this paper, an algorithm for shape optimization of structure with discrete variablesis given. First, the mathematical model of truss configuration problem is given, which include twokinds of variables such as sizing variables and joint coordinates. The objective function for trussconfiguration problem is the total weight of structure and the constraints are stress constraintsand joint displacements. In general, the structural responses, such as forces and displacementsare implicit functions of design var...

1999, 31(6): 731-738. doi: 10.6052/0459-1879-1999-6-1995-087

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SIMULATION OF THE ANNULAR SWIRLING TURBULENTFLOWS UNDER DIFFEAXNT CONDITIONS

The swirling turbulent flows in an annular duct under different conditions are nu-merically simulated with a new algebraic Reynolds stress model. The model properly accountsfor swirl-turbulence interactions and non-isotropic turbulence. The effects of swirl number, inletaxial velocity, and ratio of inner to outer radius on the annular swirling turbulent flows, and sub-sequently on enhancing heat transfer in the annular duct due to the variations in the flow fields,are investigated and analyzed. The calculat...

1999, 31(6): 739-744. doi: 10.6052/0459-1879-1999-6-1995-088

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STUDY ON INFLUENCE OF THE BOUNDARY SLIP OFVISCO-PLASTIC LUBRICANT ON THE LUBRICATIONPROPERTIES

Hydrodynamic lubrication theory based on viscous fluid mechanics has greatly devel-oped the tribology theory. However, because the mechanical equipment is developed with muchhigher speed and larger scale in recent years, lubrication failure occurs frequently. In electric gen-erator sets and mill trains, accidents caused by lubrication failure cost great lost. According tostatistics of the former Soviet Unions, 60 percent of the accidents in hydroelectric generator setsare caused by lubrication failure. The ...

1999, 31(6): 745-752. doi: 10.6052/0459-1879-1999-6-1995-089

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AN ELEMENT HARMONIC BALANCE METHOD

An element harmonic balance method based on finite element method is proposedin this paper and is used to solve nonlinear dynamic response problems. Different from generalharmonic balance method, such harmonic balance equations airs established in finite element level,making the method advantageous in both finite element method and general harmonic balancemethod. The applications of finite element method can extend the solving range to complex engi-neering structures, and the application of harmonic balance...

1999, 31(6): 753-760. doi: 10.6052/0459-1879-1999-6-1995-090

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